Because this is a sunny, cloudless day we will change the background color to a bright blue (Rendering/Environment).

Also make sure the ambient color is set to black. We will create our own fake light.

Now, on to the directional light.

The color of the light would be bright yellow, coming from the sun and all. Uncheck the specular box.
This is one of the things that give the BS look, MAX's speculars. I will cover this in the next part of the tutorial, but for now, just uncheck the box already! Now, move on to Contrast and Soften Diffusion Edge parameters. These controls the way the light affects the surface and is very critical to the overall look of the lighting. Now you have to trust your eye for how the sunlight behaves. I find that both parameters
should be around 30-40 for a good result for a cloudless day. If it was cloudy, I would go for less contrast...

Since the shadows are too blurry for this scene we will increase the size of the map, and therefore get a crispier shadow with more details.
In the Shadow Map Params rollout, Set the Size to about 3000. Set Bias to 0,0. Bias controls how close to the object the shadow will fall. Sample Range will increase the blurryness of the shadows. Make a test render to see how this looks. Not too bad, eh? We have created our sun, yay!

Now, there should be light coming from the sky... create an omni light and make 3 instances of it and place them around the scene. This will be a very basic lightsetup for skylight. 4 lights for skylight is often enough, but somtimes you need more to hide unwanted shadows. But remember that the more lights you use, the longer the rendertimes will be...

There are four things that I think is most important when you create skylighting with fill lights:

1. Color; I've seen so many images where people have put too much color in their lights. This is great for artistic non-photorealistic imagery and for creating a mood, but not for what we are trying to do here. I guess the basic rule to follow is "Warm light, cold shadows. Cold light, warm shadows."

But this needs to be executed in a subtle way. For this skylight, I choose not to put any color at all on the lights, just a dark grey. The shadows will come off as blue because of the yellow sunlight.

2. Placement; The lights should be placed so that they light the whole scene evenly. In this case, the easiest way to do this is to turn off the sunlight and move the omnis around until it gets harder to spot the edges of the objects. Everything should be shaded evenly. Then turn the sunlight on again.

3. Intensity; I can't really help here, since this is a case-to-case scenario. Just look around you and study the way light reflects. In MAX, change the Multiplier for light intensity.

4. Shadows. They are tricky. You have a few ways of hiding the unwanted shadows... you can create alot of lights and have them burn out every skylight shadow that's not where it should be. Rendertimes will be higher tho. You can blur the shadowmaps and hope that they will pass for dirt on the ground...